防盜鏈過濾器

package com.pzhu.filters;

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class ResProtectedFilter implements Filter {

	public void destroy() {

	}

	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain chain) throws IOException, ServletException {
		
		HttpServletRequest req=(HttpServletRequest)request;
		HttpServletResponse res=(HttpServletResponse)response;
		String fromUrl=req.getHeader("referer");
		String path = req.getContextPath();
		String basePath = req.getScheme()+"://"+req.getServerName()+":"+req.getServerPort()+path+"/";
		if(fromUrl.startsWith(basePath)){
			chain.doFilter(request, response);		
		}else{	
			res.sendRedirect("/pzhuweb/pro.jsp");
		}
	}

	public void init(FilterConfig filterConfig) throws ServletException {
	}
}